Sorry, citation still needed: http://www.ncbi.nlm.nih.gov/pubmed/12826028

"It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. ... This position paper reviews the current scientific data related to key nutrients for vegetarians including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine. A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients. Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life-cycle including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fibre, magnesium, potassium, folate, antioxidants such as vitamins C and E, and phytochemicals."

Notice that your citation completely agrees with my statement above but includes lots of wiggle words like "can", "appropriately planned", "well planned", "supplements" and focuses on vegetarian diets without specifying type of diet and doesn't focus on veganism as a dietary habit.

It also doesn't discuss long term dietary issues of vegan practitioners, percentage of practitioners with health deficits (ones who don't practice an "appropriately/well planned diet" and live without the use of "supplements").

Cite me some long term studies with randomly sampled population surveys and we can start having a real conversation.

I don't see anything that agrees with your original statement: "Non-animal sourced diets are hopelessly unhealthy in the long term no matter how many supplements you take to try and take to make up for it." You have yet to cite anything supporting that.

The only supplement that is strictly required on a vegan diet is B12. I'm not sure what's so inherently bad about taking a supplement anyway? Most people, regardless of diet, should be supplementing vitamin D in winter, for example.

I wouldn't want to be following any diet that isn't appropriately planned, so I don't understand your repeated scare quotes. You can be vegan eating nothing but potato chips and coca-cola, but that wouldn't exactly be well planned. Is it possible to be unhealthy on a vegan diet? You bet. Is it possible to be unhealthy on an omnivorous diet? Look at the average American.

"Is it possible to be unhealthy on an omnivorous diet? Look at the average American."

I'm not arguing that point, and I already conceded it earlier, don't misdirect.

If you think a little B12 every once in a while is the only supplement required on a vegan diet, with a little D in the winter, I hope that you aren't observing such a diet, or you've already failed in understanding even the basics of the nutritional and biological science required to even have a chance at making it work long term.

Who's misdirecting? You still haven't cited anything. I'll play along though; which nutrient(s) can only be obtained from animal sources? Even B12 is only accumulated in animal tissue, it's not produced by animals.

Anecdotally, I've been following a thoughtful vegan diet with B12 supplementation for 8 years. The results of my last blood test (including tests for various likely deficiencies) were exemplary. Could you post something other than your opinion? Otherwise, I'm done here.

I don't need to cite anything, 10 seconds on google scholar looking for long term studies will suffice for your needs.

Good luck with it and be careful.

tl;dr

Here's your 100 day challenge, get 100% of your dietary requirements from your diet (without fortification of key ingredients or supplements, just from pure foodstuffs), and prove to me that you aren't eating a poor diet.

here's the tl part:

You're overfocusing on B12, because the literature on vegan nutrition overfocuses on B12 as neurological damage caused by B12 deficiencies are generally irreversible. Dietary B12 doesn't come from many non-animal sources, but you don't need much anyway, and effects of B12 deficiencies aren't symptomatic for several years. Your pre-vegan intake of B12 would have been sufficient for a few years until you figured out non-animal sources of it. It's also unclear to date if the form of B12 found in non-animal sources (synthetic eukaryotic sources, etc.) functions identically to animal sourced (from prokaryotic sources) B12. There are almost no studies on it because you have to try and be deficient in B12 on a normal diet without large-scale intestinal disorders.

"Even B12 is only accumulated in animal tissue, it's not produced by animals."

I don't think you understand where B12 comes from, I'm sure your understanding came from some vegan promotional literature which seems woefully full of cherry picked misunderstandings and absurd apologetics.

I'm sure you're getting it through some supplement. Now get it through dietary means. Or if you actually care about the environment, get it from locally produced dietary sources alone and don't have to have some heavily processed fermented foodstuff shipped a thousand miles to your fridge. I don't need to cite anything for you to know you simply can't.

α-linolenic acid is where you'll probably have the biggest long-term health issues, as metabolism into EPA and DHA is very inefficient with most of the issues in DHA production. Multiple studies show deficiencies in vegan diets w/r to DHA. Synthesis, requires several dietary co-factors in careful balance and long term studies suggest possible liver damage in humans (but not conclusively) vs. simply ingesting animal sources of long-chain n–3 fatty acids. Most vegans eat sources of ALA thinking it will makeup for their dietary deficiencies EPA and DHA, but multiple studies show that DHA levels remain deficient in these cases.

I'm sure you take supplements to make up for this inadequacy in your diet. Now do it without them. And if you think that your non-animal sourced Omega-3 supplement is complete, think again. There is no such thing as one kind of ω−3. You need them all, but in particular you need EPA and DHA.

Oh and DHA supplements also have a nasty side effect of preventing blood clotting, damaging immune response and increasing LDL levels. In other words, don't take them, they will hurt you.

Vitamin D should also be a no-supplement required vitamin. You make it in your skin for goodness sakes! It's not really essential, but it's plentiful in animal sources, and just stepping out in the sun for a bit everyday is more than sufficient to produce all the D secosteroid you could ever possibly need. If you feel the need to take D supplements, for all that is holy, take D3 and not D2 as the bio-availability of D3 is several times higher than D2. But of course, if you're taking "vegan-friendly" D supplements, it's almost always a fungal source which of course is the deficient D2 ergocalciferol form. I would suggest UV lamps at your desk instead of supplements.

I'm sure you already know about Iron and Zinc deficiencies in your diet. Every vegan I know is acutely aware of it and tries to eat lots of iron and zinc rich food stuffs and takes yet again more supplements to make up for their shitty diet.

But look, the point is this: the definition of a poor diet is a diet that doesn't provide for all of the necessary nutrients as part of the diet. If you have to take supplements to make up for dietary shortfalls, your diet is a poor one...period. Waiving away the handful of supplements you take everyday is madness and a serious problem.

Vegans are among the only otherwise healthy population group in the developed world that routinely suffers from illnesses seen only in the most decrepit poverty stricken parts of the undeveloped world. Most vegans source their information from highly biased vegan promotional material and don't understand the basic science.

I get it, you want to help the animals out of some sort of moral obligation. And I'm sure you only eat food produced on farms with no field kills, and use the parts of the internet only on a machine powered by sources that have no animal impact. And that somehow you live in a vegan mecca where somehow all of the various plants that produce 100% of your dietary requirements don't have to be shipped from halfway around the planet killing goodness knows how many animals in the process and that you believe in a world where everybody else goes vegan and the billions of domesticated farm animals somehow continue to find sponsorship for their care and maintenance in perpetuity. I think that's great.

Just be careful, and proceed with the understanding that long-term, you won't be able to sustain this diet without compromises to your health.

"But look, the point is this: the definition of a poor diet is a diet that doesn't provide for all of the necessary nutrients as part of the diet. If you have to take supplements to make up for dietary shortfalls, your diet is a poor one...period. Waiving away the handful of supplements you take everyday is madness and a serious problem."

That's simply your opinion. You're obsessed with the evils of supplements. Who cares if you need a couple of supplements to make up for some known shortfalls? It's a trivial part of my day, and it's hardly a "handful of supplements". Besides, consuming animal products has its own set of drawbacks.

I'm not sure why the vegans you know are so concerned about iron and zinc. I'm deficient in neither and don't go out of my way to supplement them. They're readily available in many plant foods. I'm also well aware that vitamin D is produced in skin, but you might want to double check your latitude if you're relying on that in the winter.

My goal is not to get 100% of my dietary requirements from food. That's apparently your objective. I never claimed a vegan diet can provide all the nutrients you need without supplementation. I readily admit you have to take B12. Some other things might be good to supplement too, depending on the actual make up of your diet. This is true even if you are omnivorous.

This whole thread started because you made this claim: "Non-animal sourced diets are hopelessly unhealthy in the long term no matter how many supplements you take to try and take to make up for it"

And now you've added:

"Vegans are among the only otherwise healthy population group in the developed world that routinely suffers from illnesses seen only in the most decrepit poverty stricken parts of the undeveloped world."

Please cite something specific to support either of those claims. "Google it" is not a citation. I know a lot of long term vegans (multiple decades; some lifelong) who are doing just fine.

If anyone else is still following this thread, this is a good source of information for vegans who want to be healthy: http://veganhealth.org

Yes, if anybody is still on this thread, and you want to go vegan, or are currently practicing, please please please, read the relevant appropriate scientific literature and don't just rely on vegan promotional sites like veganhealth.org (which makes several of the dietary mistakes I noted earlier in the thread).

Don't rely on opinion, tips at Whole Foods, friends, the internet, vegan pamphlets, support groups or only promotional websites. For example, veganhealth.org (run by dietition Jack Norris) makes an good effort at being a good guide - Jack does a pretty good job of distilling lots of the hard stuff into digestible chunks (forgive the pun). But it's subject to the exact same pitfalls and hopeful thinking (a bit of ground flaxseed on toast will solve all your omega problems!) I've seen in dozens upon dozens of vegan promotional dietary guides.

Once you've decided to go vegan, you've made the jump to accepting that you will be eating an inadequate diet to start with. (Simple logic dictates that if you need supplements to fix gaps in your diet, it's inadequate in those areas). Maintaining proper nutrition and health is unbelievably complicated when you're starting at such a disadvantage.

See a doctor regularly and demand the appropriate blood tests that test for the specific dietary deficiencies that are normal on a vegan diet. Don't rely on a typical blood panel...which is designed for people on omnivorous diets -- diets for which almost all of the vegan dietary deficiencies simply don't occur. If you don't know what the tests are, it's time to start your research!